ideal classic RS250 kettling

[cypher007]

that one was out of stock. but ive ordered the same sort of thing.

once I get it how do I go about testing? do I run the system upto temp then measure the drop between flow and return?

p.s. my concern regarding the system setup stems from the fact the boiler may have been put in by the previous owner, who I think had scant regard for regulation or proper setup. ontop of this the plumber who put in the unvented fitted a secondhand pump. that's another thread of its own.

 

[Agile]

Fitted a second hand pump which failed shortly afterwards, forgot to notify or fill in Benchmark.

Also fitted the tun dish wrongly too!

Run the heating until the system is fairly warm and then measure flow and return while the boiler has been firing for about 2-3 minutes!

Tony

 

[cypher007]

still not sure if the pump is fubar, as the downstairs rads do get hot.

 

[cypher007]

ran the boiler from cold heating just the unvented hot water tank.

boiler started kettling after about 1 min.

7 mins 40c flow 7-8c difference.
15 mins 43c flow 8c difference.
20 mins 45c flow 10c difference.
25 mins 46c flow 9-10c difference.
30 mins 48c flow 10c difference.
35 mins 51c flow 7c difference.
40 mins 52c flow 6-7c difference.
45 mins 54c flow 7c difference.
50 mins 56c flow 7c difference.
55 mins 57c flow 7c difference.

 

[pallen5000]

Could he have the flow and return pipes crossed over?

 

[spraggo]

I would suspect that the internal pump return spreader/injector is partially blocked.

spraggo

 

[cypher007]

they were crossed, but I got them back to sort it.

 

[cypher007]

I would suspect that the internal pump return spreader/injector is partially blocked.

spraggo

bummer.

could a knacked pump do the same?

Im gonna try a different one at the weekend.

if it is blocked whats likely to shift it?

 

[Agile]

The small temperature differential indicates that there is a very good flow through the boiler so the pump will be working fine!

Actually higher than needed. A differential of 11 C is the target for that boiler design.

It will vary according to what you are heating. It was not clear to me what you were heating.

Tony

 

[cypher007]

I was heating our hot water tank.

if theres good flow whats causing the heat exchanger to boil at the bottom? thin walls? burner pressure?

 

[Agile]

"To boiler" ?

Its better to do these temperature tests on heating only. As that represents the situation for over 90% of the time.

Tony

 

[cypher007]

sorry ill redo the test using just the rad circuit.

 

[cypher007]

only did about 10mins this time. this is after the boiler had been on maybe 20 mins.

the temp drops are the boiler stat cycling, which is set to 5.

64 flow 13 diff
61 flow 10 diff
65 flow 15 diff
67 flow 16 diff
68 flow 16 diff
69 flow 16 diff
69 flow 16-17 diff
70 flow 18 diff
68 flow 15 diff
66 flow 13 diff

interestingly when I checked the pump it was running at 6W. but when its feeding the HW it runs at 49W. its an Alpha Pro 25-60 its set to the auto mode.

 

[Agile]

Water has a different viscosity when its hot!

Probably better to have the pump on manual setting for these measurements.

Also better to do it at a lower temperature with boiler stat turned to max to ensure the stat is not causing boiler to turn off during measurement time.

They are so variable that although some are fine others are rather high and making me think there was a flaw in the measurement techniques.

Tony

 

[cypher007]

ok pump on setting 3

system had been on an hour about 2 hours earlier.

0 min 31 diff 6
5 min 36 diff 8
7 min kettling
10 min 41 diff 9
15 min 45 diff 9
20 min 49 diff 9-10
25 min 51 diff 8
30 min 58 diff 12
35 min 62 diff 12-13
40 min 64 diff 11
boiler stat trip at about 65
45 min 63 diff 10
boiler stat trip at 69
50 min 67 diff 10
55 min 69 diff 14